Retrofit of low head dams in North Dakota and Colorado
See the picture is of a former low head
dam that now has a rock rapids built on the front. (Midtown
dam, Fargo ND (see fact sheet)
Here's some info that might be of interest to CCB directors:
Subject: American Fisheries Society and artificial rapids
Dakota Chapter Newsletter November 1999 5 Rock Rapids Below Low-Head
Dams Increase Human Safety & Fish Habitat (NDGF News Release)
Low-head dams. Their purpose: to store river water for times of
drought. During normal flows, water rolls lazily over them to the
river's natural level below. These structures may appear
unthreatening, but over the years they have claimed so many lives
they have been dubbed "drowning machines." Additionally, they
seriously impact the fishery by preventing fish from swimming
upstream to spawn.
Just below Kidder Dam, on the Red River at Wahpeton, the North Dakota
Game and Fish Department and Minnesota Department of Natural
Resources are constructing an artificial rock incline or rock rapids
to alleviate these problems. The artificial rapids will not only
reduce the danger to humans but also will improve the fishery by
lessening the impediment to fish movement, reports Lynn Schlueter,
eastern district fisheries supervisor, Devils Lake. Low-head dams are
dangerous because of the hydraulic effect created when water flows
over them. As water drops over the dam into the plunge pool below, an
undertow is created, rolling the water toward the face of the dam,
often pulling objects from downstream into the turbulence. These
effects multiply as the volume of water increases. The hydraulic also
extends farther downstream. Low-head dams are not viewed as a safety
hazard by many people, Schlueter said. "I've watched a gallon jug go
under in a plunge pool and pop up downstream below the dam a few
minutes later. Then it is sucked back upstream where it goes through
the hydraulic again. This repeats over and over. A human has no
chance when this happens."
In the Kidder Dam project field stone and large rocks will be placed
in the plunge pool to build a five percent incline extending to the
top of the dam. The incline will dissipate some of the energy created
as water drops over the dam, effectively eliminating the undertow. In
effect, it simulates a rapid in a high mountain river, a natural
adjustment for sudden change in stream bed elevation. And, fish can
swim up the man-made rapids and over the dam except when river flows
are extremely low. According to Schlueter, the game and fish
department would consider putting rock rapids in other rivers, "where
they could be an asset to aesthetics, people use, and fish passage."
They can also be used to shore up existing dams with structural
problems. Not only will the man-made rapids at Kidder Dam allow for
fish movement, but also they will provide increased habitat
complexity, expected to benefit species such as walleye, sauger,
channel catfish, and the recently reintroduced lake sturgeon.
Walleye, Schlueter hopes, may even spawn in the rock rubble and
northern pike, catfish, and lake sturgeon can access tributaries
upstream.
The first Red River rock rapids was completed at Mid-Town Dam in
Fargo, where it has effectively solved issues similar to those at
Kidder Dam. Minnesota's DNR also has used the process in several
places. For example, the DNR constructed a similar system where the
Otter Tail River runs out of Lake Breckenridge. According to
Schlueter, Minnesota fisheries biologists have netted a number of
fish species moving upstream from the river into the lake where they
previously could not have done so. Bowman-Haley Dam near Bowman, N.
Dak., has a similar structure that appears to be achieving its goal
of allowing fish to move upstream and which also serves to increase
dam safety, Schlueter said. In addition to the Minnesota and North
Dakota fisheries divisions, the Kidder Dam project includes the
cooperative involvement of the city of Wahpeton and Wahpeton Park
Board, Wilkin County Soil and Water Conservation District, Otter Tail
River Revival Group, and Wilkin County Environmental Office.
Government entities interested in learning more about rock rapids are
asked to contact North Dakota fisheries chief Terry Steinwand for
details at 701-328-6349.
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Page 6
Dakota Chapter Newsletter November 1999
I have a follow-up report:
Subject: Follow-up on Red River rock dams
ADVERTISEMENT
I spoke with Wayne Beyer in Wahpeton, ND. He is the Parks director,
701-642-2811.
He said the Red River is about 110 ft. across, and the depth from the
top of the dam to the river bottom was 16 ft. The cost to fill in
the area below the dam was $120,000. Earlier dams cost a lot more,
but the costs have dropped dramatically as the engineers got smarter
and more experienced.
The rock dam at Wahpeton is considered Class 2 rapids, and there are
warning signs that the boater is approaching a rock dam.. There is a
portage trail and access points above and below the dam. No boat
chute or whitewater course here, but paddlers may and do run the
rapids.
The fisherman complained a little, but the dam has not harmed the
fishing and the fish can move more freely in the river, he said. The
rock dam creates nice holes for the fish and most stay put.
An engineer with Minnesota DNR has designed the rock dam at Wahpeton
and in Fargo. He is Luther Aadland, 218-739-7576.
Who says this would cost a million $? We could do all the low head
dams on the Des Moines for that. Plus, put in boat chutes and a
whitewater course.
Gerry Rowland
Des Moines
Union Ave. boat chutes, Englewood, CO
I watched the Union Ave. boat chute video, very
interesting. It's
about 15 minutes long.
The boat chutes are in the Denver area, actually in the city of Englewood.
There was a low head dam where 2 kayakers and a fisherman died in the
mid to late 80's.
A community petition with hundreds of signatures led to a project
with the Colorado Conservation Board and the Dept. of the Interior
Bureau of Reclamation based on a design by Gary Hale (sp)
The project was completed in the mid-90's. There are a series of
chutes, each with a rock covered "ramp" and a gentle chute. There
appear to be wave features at the end of some of the chutes. There
are a series of pools, each progressively lower, after each chute.
The video shows rafters and paddlers going down the chutes, plus
people holding on to float boards. It also shows people walking
across the ramps and swimming below the chutes. It looks as though
each ramp/chute drops only a few feet. The "rules and regulations"
sign shown at the end says that only expert boaters can use the
chutes in high-water conditions.
I think I'll show this video at expo, I really appreciate the concern
for safe boating shown by the officials at the dedication.
This is such a contrast to "the stupid kayakers deserve to die"
approach that some Iowans seem to relish.
Low head dams are not an act of God or an act of nature. They are
something we can and should fix.
Gerry Rowland
Des Moines
Red River of the North
Conversion of a dam to a rapids
Fargo, ND/Moorhead, MN
Fact sheet:
Date started: Feb. 1998
Date completed: Feb. 1999
Materials used: 4400 cubic yards of rock ranging from crushed rock to 5 ft. boulders
Equipment used: two large excavators, dragline, front end loader
Total cost: $228,234
Partners: MN DNR, Fargo, ND, Moorhead, MN, Buffalo and Red River Watershed Boards,
ND Dept. of Game and Fish, River Keepers
Dams cause environmental and societal damage. They can create dangerous hydraulic rollers that trap and drown people; they prevent fish and other aquatic animals from migrating upstream to high-gradient habitants; they prevent sediment from moving downstream; and they act as barriers to people travelling up and down the river.
Removing these dams eliminates all of these problems, but when that is not an option, converting the dam to a rapids is the next best thing. This fills the scour hole below the dam, eliminating the hydraulic roller and making the dam safer, and enables fish to migrate upstream.
Midtown dam, which was built in 1960, was not removed because the city wanted to maintain a water intake pipe in the pool above the dam. Therefore, work began in February 1998 to convert Midtown Dam to a rapids. After delays caused by high water, the project was completed in February 1999. Since that time, the site has become a popular kayak run. This project is part of a larger effort to "Reconnect the Red" which will make all of the dams along the Red River of the North-from Winnipeg, Canada to Fergus Falls, MN-passable to fish.
For more information contact:
Stream Habitat Program
Division of Ecological Services
Minnesota Dept. of Natural Resources
